The subject of this invention is the design of a new type of direct vision periscope. This periscope is designed to meet requirements for a dramatic increase in the vertical field of regard over existing periscope designs. Here, field of regard refers to the number of degrees of visual data available to the sensor when sensor movement is allowed. Existing periscope designs for military applications do not allow a soldier to see an enemy on elevated areas or rooftops in an urban combat setting. This lack of vision capability places greater risks on the soldiers and their equipment. A periscope with a greater vertical field of regard would offer improved capability for area surveillance and hence soldier survivability and safety.
There are no simple direct vision periscopes currently designed that can achieve a vertical field with a range of view of an estimated −24° to +59°. For example, the wide angled rapezoidal periscope described in U.S. Pat. No. 4,934,246 provides for a low glint reflection, laser eye safe filters and ballistic features. However, vertical field of regard is limited by mirror placement within the periscope body. One way to increase the field of regard is with moveable optical systems. However, there is always an issue of reliability with complex moveable mirror systems. No current direct vision periscope has the capability of seeing such a large vertical field of regard in a passive device without adjustable mechanism such as moveable or rotating mirrors or moveable mounting devices.
Thus there is a need for periscopes with an increased field of regard obtained passively. The system should not require the operator to make manual adjustments to the viewing system components or to the mounting angle. The periscope should be trapezoidal in shape to take advantage of close semicircular mounting when used in combination with other periscopes to achieve a panoramic exterior view without blind spots. The periscope should also provide ballistics, low glint and laser eye safe filters.